docs: def dim(self, dim_index):
          """Get an SDim instance given a dimension index number.
  
          Args::
  
            dim_index index number of the dimension (numbering starts at 0)
  
          C library equivalent : SDgetdimid
                                                      """
          id = _C.SDgetdimid(self._id, dim_index)
          _checkErr('dim', id, 'invalid SDS identifier or dimension index')
          return SDim(self, id, dim_index)